全文获取类型
收费全文 | 4705篇 |
免费 | 519篇 |
国内免费 | 238篇 |
出版年
2024年 | 25篇 |
2023年 | 112篇 |
2022年 | 152篇 |
2021年 | 256篇 |
2020年 | 238篇 |
2019年 | 357篇 |
2018年 | 212篇 |
2017年 | 136篇 |
2016年 | 134篇 |
2015年 | 176篇 |
2014年 | 333篇 |
2013年 | 315篇 |
2012年 | 221篇 |
2011年 | 218篇 |
2010年 | 200篇 |
2009年 | 193篇 |
2008年 | 218篇 |
2007年 | 208篇 |
2006年 | 188篇 |
2005年 | 150篇 |
2004年 | 96篇 |
2003年 | 97篇 |
2002年 | 112篇 |
2001年 | 53篇 |
2000年 | 64篇 |
1999年 | 52篇 |
1998年 | 59篇 |
1997年 | 46篇 |
1996年 | 44篇 |
1995年 | 44篇 |
1994年 | 44篇 |
1993年 | 43篇 |
1992年 | 43篇 |
1991年 | 57篇 |
1990年 | 31篇 |
1989年 | 34篇 |
1988年 | 27篇 |
1985年 | 26篇 |
1984年 | 64篇 |
1983年 | 37篇 |
1982年 | 42篇 |
1981年 | 30篇 |
1980年 | 34篇 |
1979年 | 40篇 |
1978年 | 26篇 |
1977年 | 30篇 |
1976年 | 24篇 |
1975年 | 22篇 |
1973年 | 19篇 |
1972年 | 20篇 |
排序方式: 共有5462条查询结果,搜索用时 15 毫秒
1.
Bugreev D. V. Sinitsyna O. I. Buneva V. N. Nevinsky G. A. 《Russian Journal of Bioorganic Chemistry》2003,29(3):249-261
Data on the interaction of DNA type I topoisomerases from the murine and human placenta cells with specific and nonspecific oligonucleotides of various structures and lengths are summarized. The relative contributions of various contacts between the enzymes and DNA that have previously been detected by X-ray analysis to the total affinity of the topoisomerases for DNA substrates are estimated. Factors that determine the differences in the enzyme interactions with specific and nonspecific single- and double-stranded DNAs are revealed. The results of the X-ray analysis of human DNA topoisomerase I are interpreted taking into account data on the comprehensive thermodynamic and kinetic analysis of the enzyme interaction with the specific and nonspecific DNAs. 相似文献
2.
《Cell reports》2020,30(3):807-819.e4
- Download : Download high-res image (268KB)
- Download : Download full-size image
3.
4.
Immediate fragmentation of parental DNA by near-ultraviolet irradiation at 313 nm was measured in cultured skin fibroblasts from normal individuals, patients with Xeroderma pigmentosum of complementation group A (XPA) and Xeroderma pigmentosum variants (XPV) by the alkaline elution procedure. For a dose of 2.25 KJm?2 given at Oo fragmentation was comparable in all cell strains. However, fragmentation was strongly increased relative to Oo in XPV but not in normal fibroblasts and the XPA strains when irradiation was carried out at 37o. From our results it appears that a step in the repair of DNA is abnormal in XPV. 相似文献
5.
《Cell reports》2020,30(7):2055-2064.e5
- Download : Download high-res image (99KB)
- Download : Download full-size image
6.
M. Zamirul Hussain John C. Belton Rajendra S. Bhatnagar 《In vitro cellular & developmental biology. Plant》1978,14(9):740-745
Organ cultures of newborn rat lungs synthesize and accumulate DNA, RNA, collagen and noncollagenous proteins almost at a linear
rate for at least 5 days. During this period the synthesis of collagen consistently exceeds the synthesis of noncollagenous
proteins in a pattern similar to neonatal lung growth in vivo. Although some morphological characteristics of lung architecture
are distorted after culture, fundamental structural similarities to lungs growing in intact animals are retained. When these
cultures are maintained in atmospheres rich in oxygen, increased collagen synthesis is observed, a response similar to that
of lungs in intact animals exposed to high oxygen concentrations in vivo. Our studies suggest that lung organ cultures may
be a suitable system for investigating the biochemical aspects of lung tissue-environmental interaction.
These studies were supported in parts by NIH Grant HL-19668, a contract (68-03-2005) from the U.S. Environmental Protection
Agency, and grants from the California Lung Association. 相似文献
7.
本文就粗品肝素钠生产的原料控制硬件设施管理和环保等方面进行了论述,介绍了一些改进的方法和措施,并就该方面的的一些问题进行了探讨,提出了解决的方法。 相似文献
8.
9.
10.
Many lung disease processes are characterized by structural and functional heterogeneity that is not directly appreciable with traditional physiological measurements. Experimental methods and lung function modeling to study regional lung function are crucial for better understanding of disease mechanisms and for targeting treatment. Synchrotron radiation offers useful properties to this end: coherence, utilized in phase-contrast imaging, and high flux and a wide energy spectrum which allow the selection of very narrow energy bands of radiation, thus allowing imaging at very specific energies. K-edge subtraction imaging (KES) has thus been developed at synchrotrons for both human and small animal imaging. The unique properties of synchrotron radiation extend X-ray computed tomography (CT) capabilities to quantitatively assess lung morphology, and also to map regional lung ventilation, perfusion, inflammation and biomechanical properties, with microscopic spatial resolution. Four-dimensional imaging, allows the investigation of the dynamics of regional lung functional parameters simultaneously with structural deformation of the lung as a function of time. This review summarizes synchrotron radiation imaging methods and overviews examples of its application in the study of disease mechanisms in preclinical animal models, as well as the potential for clinical translation both through the knowledge gained using these techniques and transfer of imaging technology to laboratory X-ray sources. 相似文献